1. Field of the Invention
The present invention relates to an improved rotary shear seal hydraulic valve and, in particular, to a valve which can be made in many different configurations.
2. Description of the Background
The present invention is directed to a number of various improvements in rotary shear valve systems which improvements allow for a limited number of parts to be utilized to form a number of different valve configurations.
The subject valve has only four basic components, each of which can have a limited number of variations. With this relatively small inventory of parts, a large number of three-way and four-way valve embodiments can be made. Thus, part storage and valve assembly can be greatly simplified. This is particularly advantageous in on-site situations where parts and storage are limited and the need for rapid and versatile valve assembly and repair are great.
The subject valve is primarily useful in quadrapilot (four different pilot) controls and can provide at least five different shifting pressures in three- and four-way flow patterns. The subject valve can be manually operated with hydraulic or pneumatic override in either the three- or four-way flow patterns. It is also possible to operate the present invention with solenoid pilot valves or with hydraulic pilot operator and spring returns. The present invention finds particular application for use in systems such as that described in U.S. Pat. No. 4,467,833, the disclosure of which is incorporated herein by reference.
The previous valves of this general nature were linear in operation. The present invention is rotary which yields a number of advantages including enabling the valve to accept high return pressures.